Most of the research conducted in this laboratory was aimed at elucidating various aspects of the connectivity and synaptic chemistry of the basal ganglia in nonhuman primates. The main findings are summarized as follows. (1) The functionally segregated outflow of the basal ganglia remains largely segregated in separate channels at the level of the thalamus, but displays a much higher degree of convergence at the level of the pedunculopontine nucleus in the brainstem. These findings indicate that basal ganglia information processing is likely to be different at thalamic and brainstem levels. This will open new research avenues for understanding better the functional interactions between the pedunculopontine nucleus and the basal ganglia in normal and pathological conditions. (2) NMDA glutamate receptor subunits are much more abundant in dopaminergic neurons of the substantia nigra pars compacts (SNc) than in dopaminergic neurons of the ventral tegmental area (VTA). The se findings provide strong anatomical evidence for the role of excitotoxicity in the death of SNc dopaminergic neurons in Parkinson's disease. (3) The inputs from the intralaminar thalamic nuclei are differentially distributed among subpopulations of striatal interneurons, which suggests a high degree of specificity in the processing of thalamic information by striatal neurons. This should help to understand better the role of the thalamostriatal pathway in the functional circuitry of the basal ganglia. (4) In collaboration with Dr. Michael Kuhar of the Yerkes Center, we analyzed the distribution of a novel family of peptides in the nucleus accumbens and the gut and found that CART is expressed in specific populations of chemically characterized neurons in both the central and peripheral nervous system. The results will help to understand better the role of CART peptides in the centrally mediated phenomenon of addiction to drugs of abuse. (5) In collaboration with Dr. Denis Par[unreadable] in Laval University, Qu[unreadable]bec, Canada, the synaptic organization of intrinsic and extrinsic connections of amygdaloid nuclei in cats was analyzed. The most recent findings indicate that parvalbumin-immunoreactive GABAergic interneurons are a major target of excitatory afferents in the basolateral amygdaloid nuclei. This provides essential anatomical data to elucidate the neuronal mechanisms that underlie the inhibitory network of the amygdala. (6) In collaboration with Dr. Didier Pinault in Laval University, a project was completed on the synaptic organization of the reticular thalamic nucleus in rats. We showed, for the first time, that intrinsic dendrodendritic synapses are the anatomical substrate for neuronal synchronization in the reticular nucleus. These findings are important for understanding the role of the thalamocortical projections in controlling large-scale phenomena such as sleep and wakefulness. Disease Assoc.